I promised a friend that I would write about my duckweed production from the perspective of total honesty. So… here’s me being honest:
That “very pretty Lemna minor” that I harvested in S. Illinois a couple of weeks ago and released in my test pond was a FAIL. It died off in mass clusters within a week. I’ve never experienced anything like it. All the nutrient levels were good. pH was perfect. Yes, it did receive more sun and wind than it was used to but nothing out of the ordinary. I ended up pulling all of it out of the pond and ran a slew of tests. Turns out, that particular strain showed slight differences in frond shape and translucence compared to what I normally harvested from that site. Not that anyone ever measures translucence in duckweed, but that’s about the only way I know how to describe it. My tests showed that no matter how I coddled it, it still wanted to kick the bucket. Next stop- compost heap. I still can’t figure out what strain it is.
So. Fine. Moving right along… My sons helped me harvest 200 gallons of fresh, local Lemna turionifera from my seed pond this evening and I replanted that test pond by the muted glow of my pickup’s tail lights. It was just me, the skinny moon, a few croaking frogs and a gentle warm breeze. What a gorgeous night. Then home to feed my goldfish from the duckweed stuck in my sandals and get a hot shower.
Equipment update: I spent two days, off and on sewing a 50 ft “concentrating” net for my seed pond. It was getting old trying to reach out as far as I could with a 10 foot swimming pool pole and have to really work to get a bucket filled with duckweed. This new net was made from Dollar Tree items and a few nuts for weights. I loaded this new net into a little two man raft, clambered in and paddled around in a big circle on my seed pond, letting the net out as I went. I returned to shore and began to gently pull in my “catch.” It worked like a dream! I was able to harvest 1/3 of the entire pond in 45 minutes. (with the help of my two teen sons- can’t forget how they dug in and did the heavy carrying.)
I love the Dollar Tree.
It looks like I’m trying to climb out, but actually, I’m “kneeing” the plastic into place on a newly dug duckweed pond on my friend’s nearby farm. This is a test pond that measures 14 ft wide by 90 ft long and two feet deep. It took a couple of days to fill via a well pump and two really heavy spring downpours. The plastic is UV treated, 4 mil greenhouse plastic. Hopefully it should last four years or more. My friend is interested in growing duckweed as cattle feed supplements. I have been wanting to do a more controlled growth pond specifically for Lemna minor so it’s going to be a fun project. Many thanks to Gina McCord and family!
While it was filling, I did a bioprospecting run up to Southern Illinois and harvested 7 gallons of Lemna minor from one of my favorite finds- a little pond alongside a back country road. The owners of this pond are really nice folks and have been letting me harvest duckweed for about three years in a row now. Last year, I used 100 pounds of their duckweed to dry for a bioenergy project and did some fresh feeding tests with chickens and a few peacocks. This year, I am using their strain to seed this shallow, new pond seventy miles south of theirs. As we’ve had a really cool spring, the wild duckweed populations in my region are delayed in growth- down by 90% in volume over last year ths time. Also, certain strains that usually are predominant this time of year are nearly non-existent. (Wolffia and Spirodela polyrhiza)
I got back to two days heavy rain and didn’t get to release my new duckweed until the third day. It sat outside in a couple of ten gallon containers and stayed moist under the trees. It looked perfectly healthy when I finally did let it go in its new home. Below is a pic of the pond half-filled. I am going to plant tons of sunflowers on all sides to act as windbreaks. My initial fertilizer was some 20-20-20. I am transitioning to manure for this pond as soon as I can get a set-up for it.
The DIYer in me surfaced last week in the form of sewing up a few dozen sandbags, complete with draw strings. I’m using them in my duckweed ponds as anchors, sample bags, and of course- as sandbags. I could have bought what I needed off of eBay at a fairly reasonable price- $2.50 each but I didn’t want to wait to have them shipped. I was in a DIY mood, and wanted to try my hand at recycling stuff I had around the house. Awhile back, I lucked out with a huge amount of amazingly strong, breathable FREE woven polypropylene material that our local furniture store was throwing away. The polypropylene is used as a wrapping material around new furniture during shipping. What is so great about it is that it tears on perforated lines to be exactly the size I need for making sandbags. Once I got set up, I could crank out a bag complete with draw string every three minutes on my sewing machine. I used a zig zag stitch with nylon thread and used marine grade cording for the drawstring. I think I’ll hire one of my kids to sew more for me- 25 cents apiece ought to be about right. Then they’ll get lots of experience sewing and I’ll end up with a pile of highly usable and durable sandbags. Cool!
Back home from my duckweed ponds with a grin and muddy shoes this beautiful afternoon. Duckweed is growing well and spreading in even clusters across my primary pond. I talked one of my teens into helping me pull my duckweed pontoon out of one pond, swap styro floats for four 55 gallon drums strapped tight and lower into the aforementioned pond. It’s riding much higher in the water now and isn’t so tippy. It’s actually a bit too big for this current pond so I”ll tweak it a bit more and then move it to its final larger pond home. Will have to read up on how to build a temporary pier as I’ll need several cheap ones that I can reuse on down the road.
The styro floats are going to come in handy for a second boat- lighter construction, no roof, sort of a bare bones duckweed harvester. Solar recharge will happen on-shore instead of on the boat.
Now to fix that darned gutter that is leaking…
This is what I term “seeding” a new duckweed pond. You are looking at 20 gallons of fresh duckweed being released in a one acre pond. It’s not nearly enough duckweed as a proper seeding should result in an evenly covered initial surface. I will give it another dose tomorrow.
Note: This pond is man-made and isolated from any creeks or waterways. Always an important point to consider when siting or repurposing an existing pond.
I had to take a long tree branch and gently break up the lumps of duckweed to insure that all of the fronds have a chance to survive. In the past, I’ve not done this and the duckweed in the center of the clumps died. Waste of good plants. The gentlest way to do this is to push the lumps under the water and move around slowly. The fronds (leaves) have pockets of air in them and once freed from the tangled mass, head up to the surface right side up. Beating lumps apart just breaks roots, damages fronds and hurts newly transplanted duckweed more than it helps.
The foam triangle is from a week-long test I did to discover the primary wind direction as well as just how tasty duckweed is to the local wildlife. I know now which side of the pond needs a bit of tweaking for more protection from the wind. I was also happy to see that little if any duckweed disappeared in the taste experiment. I learned a great deal just by observing how the duckweed behaved. Some of it leaked out of the triangle and hugged the shoreline in clusters. Very interesting how it seems to congregate rather than drift away as individual plants. I’d seen that in my kiddy pools but attributed it to the relatively small dimensions of the pools themselves. Now in a one acre setting, individual fronds still cluster together, despite the enormity of their surroundings. Sort of like human behavior!
I’m sunburned and worn out, but totally happy with what I’ve accomplished on my first day of running a lemna farm. It’s not like my past experiences of growing duckweed in kiddie pools. This requires me being outdoors with lots of physical activity. More than I am used to. Note to self- get some sun block!
Today I did some wind studies with duckweed samples on my first pond. Then I unloaded a heaping pickup load of manure in a holding bin near my ponds. (Thanks David and Patty!) Gotta get some muck boots and work gloves. This job is not for the faint of heart. Then I did a closer inspection of the teeming pond water life that has sprung up almost overnight now that the weather is warm. I was delighted to see that Wolffia has made its appearance in one of the ponds. Wolffia is my favorite duckweed species. It’s the smallest and looks like green Cream of Wheat floating on the water. (only smaller) I’m seeding that pond with Lemna minor and know that as the summer progresses, one will come to dominate the pond and then the other will take its turn as the weather changes. It’s all good.
To celebrate my new discover and the fact that I didn’t have a heart attack from unloaded all that manure, I went fishing for a couple of hours. Years ago, these were stocked ponds and I’ve been concerned that there might be some surviving fish. As many species will eat duckweed, the last thing I want to worry about is having fish eat my duckweed faster than it can grow initially. Sort of hoped I could catch a few for our supper. Had a few nibbles but didn’t catch anything. I have a sneaking suspicion that those nibbles were the work of snapping turtles as I caught one sizing me up, only a foot away from my boat. This fellow had a head the size of my fist and its shell was at least 20 inches long. I”ve seen bigger in zoos, but it freaked me out with its point blank stare from bulging eyes. I had visions of it clambering up and taking a chunk out of my foot. Thankfully, the snapper slipped back down under the water and I watched it trail off, green algae streaming like a watery mane from its shell and neck.
Don’t know which will eat more duckweed- fish or turtles. Don’t know how bad the deer ticks are going to be. Don’t know if I’ll have enough trees to block the wind from pushing duckweed around. Don’t know what it is going to be like when it hits 100 degrees in July. I DO know that I am up for the challenge. It’s going to be an interesting summer.